The Environmental Protection Agency will unveil a sweeping proposal Monday that will require deep cuts in carbon emissions from existing power plants, including a 30% national target by 2030, according to two people briefed on the plan.

The EPA draft rule, a major plank of President Obama's initiative to fight climate change, will require states to develop and implement plans to cut power plant emissions of heat-trapping carbon dioxide. It will give states different reduction targets but will seek a national average — from 2005 levels — of 25% by 2020 and 30% by 2030, say those familiar with the plan.

Thwarted by Congress' inability to pass a bill to lower U.S. carbon emissions, Obama is pushing his own approach. Last June, he asked the EPA to use its authority under the Clean Air Act to limit power plants emissions, which account for the largest share — nearly 40% — of total U.S. emissions. Coal-fired facilities will be hardest hit, because they emit more carbon than other power plants.

The rule, expected to trigger legal challenges, will not take effect for at least two more years. Obama has asked the EPA to finalize it in June 2015, after which the states will have at least a year to craft their plans. If states balk at submitting them, the EPA could step in with its own version.

The proposal is expected to give states a range of emission-reduction targets with varying deadlines and options to meet them. So, states could comply by requiring plants to install pollution-control technology; setting up energy efficiency programs to reduce energy demand; or using more carbon-free energy such as solar and nuclear or cleaner-burning fuels like natural gas.

Obama pledged in 2009 to cut U.S. greenhouse gas emissions 17% from 2005 levels by 2020, and 83% by 2050. The nation's carbon emissions dipped between 2008 and 2015 but rose slightly last year.

In his Saturday radio address, Obama said cutting carbon emissions will reduce air pollution, improve health and spur a clean energy economy that can be "an engine of growth." He spoke from the Children's National Medical Center in Washington, D.C., after visiting with kids being treated for asthma and other breathing problems that he said are aggravated by dirty air.

On Sunday, Obama called a group of Senate and House Democrats to thank them for their support in advance of the EPA's announcement, according to the White House. He plans Monday to discuss the details with national health groups including the American Lung Association.

Opponents are already lining up against the proposal. Last week, the Chamber of Commerce released a report saying such regulation could raise consumer prices for electricity, kill jobs and slow economic growth.

In the GOP Saturday radio address, Wyoming's Sen. Mike Enzi said the Obama administration has "set out to kill coal and its 800,000 jobs." If it succeeds, he warned, "we'll all be paying a lot more money for electricity — if we can get it."

Obama said Saturday that the critics are wrong. "They warned that doing something about the smog choking our cities, and acid rain poisoning our lakes, would kill business. It didn't," he said in his weekly radio speech. "Our air got cleaner, acid rain was cut dramatically and our economy kept growing."

Prior to the rule's official announcement Monday morning, the EPA declined to discuss its details, some of which the Wall Street Journal first reported Sunday afternoon. "Until then the agency will not comment on any information that may or may not be in the proposal," said agency spokeswoman Liz Purchia.

The draft rule will go far beyond an EPA proposal last year to limit emissions from new power plants, and its impact will also exceed the administration's requirement that new cars and light trucks double fuel efficiency by 2025.